The present invention relates to aerosol containers and more particularly to such aerosol containers which do not require a propellant material maintained continuously in pressurized state therewithin.
Aerosol containers have been in widespread use as liquid dispensing devices. The conventional aerosol container utilizes a propellant material such as carbon dioxide or one of the fluorocarbons to pressure the liquid from the container. In this manner insecticides, deodorants, medicines and other liquids may be dispensed. However, it is known that the propellant fluid frequently constitutes a source of environmental pollution and sometimes the aerosol container represents a hazard when disposed of since the propellant material may be explosive or at the very least inflammable. Further, the conventional aerosol container is discarded once the supply of liquid dispersant is exhausted or when the supply of propellant material has been used to the extent that there is no longer sufficient pressure within the container to discharge the liquid as intended.
A spray device has been available heretofore which does not require the use of a pressurizing gas or other foreign propellant. Thus, the aforesaid disadvantages have to some extent been ameliorated. Such a device is disclosed in U.S. Pat. No. 3,777,945 issued Dec. 11, 1973 to Takamitsu Nozawa et al. The device disclosed in the patent employs a pair of slidable pistons, one of which is spring biased, to withdraw liquid from the bottom of the container and to discharge the liquid through a discharge valve at the top of the container. The device requires a rotatable cap which, by means of a ball and groove arrangement, cyclically reciprocates the lower piston to withdraw liquid from the bottom of the container and to force the liquid into an upper pressurizing chamber from which the liquid is forced to the discharge valve by the upper spring-biased piston. The construction is relatively complex, requires close tolerances and depends upon the force of a spring to develop and maintain pumping pressure to the discharge nozzle. Such a construction thus presents various points of vulnerability and would be relatively expensive to produce.